From the sublime to the ridiculous. Yesterday's New Scientist detailed what must surely be the strangest technological advance since the networked bra. The intelligent panty liner.

Really.

Some boffins, obviously with nothing better to do, have worked all the sanitary towel manufacturers into a frenzy with their ideas.

A warning before your period arrives: A series of patents filed by Proctor&Gamble describe how a panty liner impregnated (pardon the pun) with gum guaiac wood resin will react to trace amounts of blood by turning blue. This, along with a pH marker that turns red make for a purple spot on the liner about four hours before the floodgates open.

To detect ovulation: It seems that a coating of amorphous silicon [note spurious IT angle - Ed] changes in thickness in response to varying levels of hormones. This changes the path of reflected light and means that a warning spot shows up on the pad.

This is all very well, but the question remains, why on earth would anyone want to wear a panty liner for a nano-second longer than they had to? And nature has provided a very sensitive advance warning system anyway. HUGE chocolate cravings. ®